This invention relates to managing communication systems, and in particular to method and apparatus enabling a master control station to ascertain which of a number of stations using a common communication channel need service from the channel.
Operating methods are known for the control of a plurality of stations using a common communication channel in which a masterstation establishes priorities and controls all use of the channel. In order to avoid interference on the channel, a protocol is usually adopted that the operating stations will transmit only when directed to do so by a message from the master station. Since the operating stations do not initiate any communications, they cannot directly call the masterstation's attention to a need for service that arises, and it is necessary for the masterstation to send inquiries from time to time to each of the operating stations. Each operating station replies when queried by indicating what if any service it needs.